Liquid crystal display device

ABSTRACT

The present invention suppresses the spreading by wetting of an orientation film material in a liquid form toward a sealing agent applied region positioned on an outer periphery of a display region in forming an orientation film thus ensuring the uniformity of a film thickness in the display region. A pair of substrates includes orientation films on surfaces thereof which face opposing substrates. Out of the pair of substrates, the substrate on which the signal lines are formed, on a side thereof which is disposed between a region on which the sealing material is arranged and the display region and along which the signal lines extend to the outside of the sealing material from the display region, includes a first conductive layer, a second conductive layer and an insulation layer which is interposed between the first and second conductive layers between the orientation film and the substrate, the insulation layer extends in the direction at least along an outer periphery of the display region, and includes groove portion having a recessed groove which opens on the orientation film side, the first conductive layer is formed along a shape of the recessed groove, and the signal lines are formed in a state that the signal lines go around the recessed groove.

The present application claims priority from Japanese applicationJP2006-195104 filed on Jul. 18, 2006, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device, andmore particularly to a technique suitable for a control of an outerperiphery of an orientation film material in applying an orientationfilm to an inner surface of a substrate of a liquid crystal displaypanel which constitutes a liquid crystal display device.

2. Description of the Related Art

As a television device or a display device of an information terminal, aliquid crystal display device which uses a liquid crystal display panelsealing a liquid crystal material between a pair of substratesconsisting of a first substrate and a second substrate has been widelyspreading. Usually, the liquid crystal display panel which constitutesthis type of liquid crystal display device includes, on a main surface(inner surface) of one substrate out of a pair of substrates, aplurality of scanning signal lines and a plurality of video signal lineswhich intersects the plurality of scanning signal lines in an insulatingmanner. Then, one pixel is formed in a region which is surrounded by twoneighboring scanning signal lines and two neighboring video signallines, wherein a switching element which performs an ON/OFF control forevery pixel, a pixel electrode and the like are formed in one pixel. Ingeneral, a thin film transistor (TFT) is used as the switching element.Accordingly, one substrate on which the thin film transistors are formedis referred to as a thin-film-transistor substrate (TFT substrate).Further, another substrate which forms a pair with one substrate onwhich the thin film transistors are formed is referred to as a countersubstrate. Still further, when a plurality of color filters which areformed corresponding pixels formed on the TFT substrate are formed onthe counter substrate, such a counter substrate is referred to as thecolor filter substrate (CF substrate).

As the liquid crystal display panel, there have been known avertical-electric-field-type liquid crystal display panel such as aTN-type liquid crystal display panel or a VA-type liquid crystal displaypanel and a lateral-electric-field-type liquid crystal display panelwhich is known as an IPS-type liquid crystal display panel due to thedifference in a driving method of pixels. In thevertical-electric-field-type liquid crystal display panel, a counterelectrode (also referred to as a common electrode) which faces the pixelelectrode of the TFT substrate is arranged on a counter substrate side.Further, in case of the lateral-electric-field-type liquid crystaldisplay panel, the counter electrode is formed on the TFT substrate sideon which the pixel electrodes are formed, for example.

The TFT substrate and the counter substrate respectively have anorientation film having a function of controlling the direction (initialorientation) of liquid crystal molecules in a state that no potentialdifference exists between the pixel electrode and the counter electrodeand an arrangement and an inclination of the liquid crystal moleculeswhen the potential difference is generated between the pixel electrodeand the counter electrode (liquid crystal orientation control function).

The orientation film is formed on interface between respective mainsurfaces of the TFT substrate and the counter substrate and a liquidcrystal material (a liquid crystal layer) and, an orientation controlfunction is imparted to the orientation film by applying rubbingtreatment or polarized light radiation or the like to a surface of aresin film which is formed to cover the whole display region on whichpixels are arranged two-dimensionally and is preferably made ofpolyimide.

The resin film made of polyimide or the like which is formed as theorientation film on the surfaces of respective substrates consisting ofthe TFT substrate and the counter substrate is formed using a methodwhich is referred to as a aniline printing method. However, recently,there has been proposed a method which forms the orientation film usingan inkjet printing method (patent document 1). The ink jet printingmethod directly applies ink to be formed into the orientation material(orientation film material ink) to the substrate using an ink jetnozzle. The ink jet printing method is an on-contact process and hence,the method has various advantages such as the low contamination ofsubstrate surfaces or the fabrication facility, the reduction of solventconsumption quantity, shortening of process time or the like.

Patent document 1: JP-A-2001-337316

SUMMARY OF THE INVENTION

However, in forming the orientation film using the ink jet printingmethod, it has been pointed out that it is difficult to restrict aposition of a periphery of an ink applied region. That is, the viscosityof orientation-film-material ink used in the ink jet printing method islow compared to the viscosity of a material used in the aniline printingmethod and hence, when the material of the resin film which forms theorientation film by the ink jet method is applied to the substrate, itis difficult to control the position of the outer periphery of theapplied region formed along with spreading by wetting of the orientationmaterial ink which is discharged to the substrate from a nozzle of anink jet device.

Accordingly, for example, in forming the orientation film on a mainsurface of a TFT substrate on which, for example, scanning signal lines(also referred to as gate lines), video signal lines (also referred toas data lines or drain lines), TFTs, pixel electrodes and the like areformed by the ink jet printing method, there may be a case that anapplied orientation film material spreads by wetting on the main surfaceand reaches a sealing agent applied region (sealing region) which sealsa counter substrate. The orientation film reaches the sealing region,the adhesiveness of the sealing agent and the TFT substrate becomesinsufficient attributed to the presence of the orientation film materialbelow the sealing agent and the substrate. This insufficientadhesiveness gives rise to the defective sealing, the positionaldisplacement with the counter substrate or leaking of a liquid crystalmaterial.

In forming the orientation film using the inkjet printing method, toprevent the printed orientation film material ink from spreading bywetting to the sealing region, it may be possible to provide a methodwhich preliminarily decreases a region on which the orientation filmmaterial is printed by taking a spreading-by-wetting quantity of theprinted orientation material ink into consideration. However, thismethod results in narrowing an effective display region and, is liableto generate irregularities in a film thickness of the orientation filmprinted in the inside of the display region.

Besides such a method, it may be also possible to provide a method whichsuppresses spreading by wetting of the orientation film material ink tobe printed by increasing the viscosity of the orientation material ink.However, this method is liable to easily form a region where theorientation film material ink is not applied due to an injection failure(clogging of a nozzle) at the time of printing.

It is an object of the present invention to provide a liquid crystaldisplay device having the structure which, for example, in forming anorientation film in a manufacturing process of a liquid crystal displaypanel, can suppress undesired spreading by wetting of an orientationfilm material in an outer peripheral portion of a display region and, atthe same time, can maintain the uniformity of a film thickness of theorientation film within the display region.

To explain the summary of the typical constitution of the presentinvention for achieving the above-mentioned object, the constitution isas follows. That is, a liquid crystal display device includes a displaypanel in which an annular sealing material is arranged between a pair ofsubstrates, a liquid crystal material is sealed in a space surrounded bythe pair of substrates and the sealing material, a display region isformed in the inside of a region surrounded by the sealing material in aplan view, and signal lines which extend to the outside of the sealingmaterial from the inside of the display region are formed on one of thesubstrates, wherein the pair of substrates have orientation films onsurfaces thereof which face opposing substrates, out of the pair ofsubstrates, the substrate on which the signal lines are formed, on aside thereof which is disposed between a region on which the sealingmaterial is arranged and the display region and along which the signallines extend to the outside of the sealing material from the displayregion, includes a first conductive layer, a second conductive layer andan insulation layer which is interposed between the first and secondconductive layers between the orientation film and the substrate, theinsulation layer extends in the direction at least to an outer peripheryof the display region, and includes groove portion having a recessedgroove which opens on the orientation film side, the first conductivelayer is formed along a shape of the recessed groove, and the signallines are formed in a state that the signal lines go around the recessedgroove.

Here, various modifications are conceivable without departing from thetechnical concept of the present invention described in claims.

The surface of the region in the extending direction of the signal lines(particularly, the scanning signal lines) formed on the substrate, thatis, in the direction for pulling out the signal line to a drive circuitfrom the display region has small irregularities. By forming therecessed groove in such a portion, it is possible to prevent spreadingby wetting of the orientation film material ink.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view showing the schematic constitution of aliquid crystal display panel of an embodiment 1 according to the presentinvention;

FIG. 2 is a cross-sectional view taken along a line A-A′ in FIG. 1;

FIG. 3 is a cross-sectional view showing a schematic structural exampleof a region AR1 on a gate side in FIG. 1;

FIG. 4 is a plan view as viewed from above in FIG. 3 showing theschematic structural example of the region AR1 in the gate side in FIG.1;

FIG. 5 is a schematic plan view showing a vicinity of a firstorientation film outer periphery restricting portion in an enlargedmanner;

FIG. 6 is a cross-sectional view taken along a line B-B′ in FIG. 5;

FIG. 7 is a view for explaining spreading of the orientation filmmaterial ink when such a material ink is applied;

FIG. 8 is a schematic cross-sectional view taken along a line C-C′ inFIG. 7;

FIG. 9 is an explanatory view of a second orientation film outerperiphery restricting portion;

FIG. 10 is a plan view of an essential part of a drain side of a TFTsubstrate indicated by symbol AR2 in FIG. 1 which schematically showsthe schematic constitution of a liquid crystal display panel of anembodiment 2 according to the present invention;

FIG. 11 is a schematic plan view showing the schematic constitution of aregion AR3 shown in FIG. 10 in an enlarged manner;

FIG. 12 is a schematic cross-sectional view taken along a line D-D′ inFIG. 11;

FIG. 13 is a schematic plan view showing the schematic constitution of aregion AR4 shown in FIG. 10 in an enlarged manner;

FIG. 14 is a schematic cross-sectional view taken along a line E-E′ inFIG. 13;

FIG. 15 is a schematic cross-sectional view for explaining a function ofa third orientation film outer periphery restricting portion Z3 forsuppressing a spreading of the orientation film material ink by wetting;

FIG. 16 is a schematic plan view for explaining a modification of agroove portion formed on the drain side of the TFT substrate;

FIG. 17 is a schematic cross-sectional view taken along a line F-F′ inFIG. 16;

FIG. 18 is a plan view of an essential part of the drain side of the TFTsubstrate indicated by symbol AR3 in FIG. 10 in the same manner as FIG.11 which explains the modification of the third orientation film outerperiphery restricting portion Z3 formed on the liquid crystal displaypanel of the embodiment 2 according to the present invention;

FIG. 19 is a partially enlarged view of a part of the third orientationfilm outer periphery restricting portion Z3 in FIG. 18;

FIG. 20 is a plan view of an essential part of the drain side of the TFTsubstrate indicated by symbol AR3 in FIG. 10 in the same manner as FIG.18 which explains another modification of the third orientation filmouter periphery restricting portion Z3 formed on the liquid crystaldisplay panel of the embodiment 2 according to the present invention;

FIG. 21 is a partially enlarged view of a part of the third orientationfilm outer periphery restricting portion Z3 in FIG. 20;

FIG. 22 is a schematic plan view showing the schematic constitution ofthe TFT substrate in a region AR5 shown in FIG. 1 in an enlarged manner;

FIG. 23 is a schematic cross-sectional view taken along a line G-G′ anda line H-H′ in FIG. 22 respectively;

FIG. 24 is a schematic cross-sectional view for explaining anothermodification of the groove portions formed in the opposite gate side andthe opposite drain side of the TFT substrate;

FIG. 25 is a schematic cross-sectional view for explaining still anothermodification of the groove portions formed in the opposite gate side andthe opposite drain side of the TFT substrate;

FIG. 26 is a schematic cross-sectional view for explaining still anothermodification of the groove portions formed in the opposite gate side andthe opposite drain side of the TFT substrate;

FIG. 27 is a schematic plan view showing one constitutional example ofone pixel of the display region of the TFT substrate as viewed from aviewer's side;

FIG. 28 is a schematic cross-sectional view taken along a line J-J′ inFIG. 27; and

FIG. 29 is a schematic cross-sectional view taken along a line K-K′ inFIG. 27.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, best modes for carrying out the invention are explained indetail in conjunction with embodiments by reference to drawings. Here,in drawings of respective embodiments explained herein after, partshaving identical functions are given the same symbols and their repeatedexplanation is omitted.

Embodiment 1

FIG. 1 is a schematic plan view showing the schematic constitution of aliquid crystal display panel of an embodiment 1 according to the presentinvention. Further, FIG. 2 is a cross-sectional view taken along a lineA-A′ in FIG. 1. The liquid crystal display device of the embodiment 1 isconstituted of the liquid crystal display panel which includes a firstsubstrate SUB1 which forms one of substrates which are adhered to eachother, a second substrate SUB2 which forms another substrate, a sealingregion SL which is arranged annularly along a periphery of a gap definedbetween opposing surfaces of the first substrate SUB1 and the secondsubstrate SUB2, and a liquid crystal layer which is sealed in a spacesurrounded by the first substrate, and the second substrate and thesealing region, wherein a display region DA is formed inside the sealingregion. The display region DA for displaying a video or an image isformed in a region where the first substrates SUB1, the second substrateSUB2 and the liquid crystal layer LC overlap each other in a plan view.

Further, in this embodiment, the first substrate SUB1 and the secondsubstrate SUB2 differ from each other in a profile size in a plan view.When the liquid crystal display device is a relatively large-sizeddisplay device such as a television receiver set or a display for apersonal computer, the first substrate SUB1 and the second substrateSUB2 overlap each other along one side out of two sides (long sides)parallel to the x direction in FIG. 1 and along one side out of twosides (short sides) parallel to the y direction in FIG. 1 in a planview.

Further, the first substrate SUB1 which is a larger substrate out of apair of substrates is also referred to as a thin film transistor (TFTsubstrate). Although not shown in the drawing, on the thin filmtransistor substrate, for example, a plurality of scanning signal lines(gate lines) which extends in the x direction in FIG. 1 and a pluralityof video signal lines (data lines) which extends in the y direction inFIG. 1 are formed. Further, in the TFT substrate SUB1, a regionsurrounded by two neighboring scanning signal lines and two neighboringvideo signal lines constitutes a pixel region in which one pixel isformed and a TFT and a pixel electrode are arranged in each pixelregion.

Further, the second substrate SUB2 which is a smaller substrate out ofthe pair of substrates is also referred to as a counter substrate. Whenthe liquid crystal display panel is a RGB color liquid crystal displaypanel, one color pixel is constituted of three sub pixels and, on thecounter substrate 2, a red (R) color filter, a green (G) color filterand a blue (B) color filter are arranged for respective sub pixels.

Further, when the liquid crystal display panel adopts a driving methodwhich is referred to as a vertical electric field method such as a TNmethod or a VA method, for example, a counter electrode (also referredto as a common electrode) which faces the pixel electrodes of the TFTsubstrate SUB1 in an opposed manner is formed on thecounter-substrate-SUB2 side. Further, when the liquid crystal displaypanel adopts a driving method which is referred to as a lateral electricfield method such as an IPS method, for example, the counter electrodesare formed on the TFT-substrate-SUB1 side.

Further, out of two short sides a, b of the TFT substrate SUB1 which arearranged in parallel to they direction, the short side a which does notoverlap a side of the counter substrate SUB2 is a side to which, forexample, a driver IC (scanning signal line drive circuit chip) forinputting scanning signals to respective scanning signal lines, or a COFor a TCP on which the driver IC is mounted is connected. Further,respective scanning signal lines are connected to gates of the TFT whichare arranged in respective pixel regions. Accordingly, in the followingexplanation, the short side a to which the driver IC for inputting thescanning signals, the COF or the TCP on which the driver IC is mountedor the like is connected is referred to as a gate side and another shortside b which is parallel to the gate side is referred to as an oppositegate side.

Further, out of two long sides c, d of the TFT substrate SUB1 which areparallel to the x direction, the long side c which does not overlap aside of the counter substrate SUB2 is a side to which, for example, adriver IC for inputting video signals (also referred to as grayscalesignals) to respective video signal lines (data lines or drain lines), aCOF or a TCP on which the driver IC is mounted or the like is connected.Further, respective video signal lines are connected to drains of theTFT which are arranged in respective pixel regions. Accordingly, in thefollowing explanation, the long side c to which the driver IC forinputting the video signals, the COF or the TCP on which the driver ICis mounted or the like is connected is referred to as a drain side andanother long side d which is parallel to the drain side is referred toas an opposite drain side. Here, as other constitution, a space may beformed on both sides of the first substrate SUB1 in the x direction anda scanning signal line drive circuit chip may be mounted on both shortsides or a space may be also formed on both sides of the first substrateSUB1 in the y direction and a video signal line drive circuit chip maybe mounted on the respective long sides.

FIG. 3 is a cross-sectional view showing a schematic structural exampleof a region AR1 on a gate side in FIG. 1. Further, FIG. 4 is a plan viewas viewed from above in FIG. 3 showing the schematic structural exampleof the region AR1 on the gate side in FIG. 1. In FIG. 3 and FIG. 4,scanning signal lines GR are formed on a main surface of the TFTsubstrate SUB1. The scanning signal lines GL are formed of oblique lineson a display region side. A first insulation layer PAS1 is formed on thescanning signal lines GL, and a second insulation layer PAS2 is formedon the first insulation layer PAS1.

On an end portion of a gate side a of the TFT substrate SUB1, an openingwhich is formed in the first insulation layer PAS1 and the secondinsulation layer PAS2 and a scanning line terminal GLT which is arrangedin the vicinity of a periphery of the opening and forms a transparentconductive film TE thereon are formed. Further, a region indicated bysymbol DA is a display region, and a first orientation film outerperiphery restricting portion Z1 is arranged in an outer peripheralportion close to the display region DA. Below the first orientation filmouter periphery restricting portion Z1, a common bus line CBL which isformed between the first insulation layer PAS1 and the second insulationlayer PAS2 is arranged, a recessed groove formed in the secondinsulation layer PAS2 is covered with a transparent conductive film TEwhich is preferably made of ITO, and the transparent conductive film TEis connected with the common bus line CBL which constitutes a conductivelayer on a bottom portion of the recessed groove.

Symbol SL indicates a sealing region. A second orientation film outerperiphery restricting portion Z2 is formed inside the sealing region SLat a position away from the first orientation film outer peripheryrestricting portion Z1 in the scanning line terminal GLT direction. Thesecond orientation film outer periphery restricting portion Z2 is formedof one or a plurality of slits ST which is formed by linearly removingthe transparent conductive film TE which is formed on the secondinsulation layer PAS2. Here, the transparent conductive film TE isterminated at the second orientation film outer periphery restrictingportion Z2 and does not reach the sealing region SL.

FIG. 5 is a schematic plan view showing a vicinity of the firstorientation film outer periphery restricting portion in an enlargedmanner. FIG. 6 is a cross-sectional view taken along a line B-B′ in FIG.5. In the liquid crystal display panel of this embodiment, in thevicinity of an outer periphery of the display region arranged close tothe gate side a of the TFT substrate SUB1, outside the display region DAin which the pixel regions each of which is surrounded by twoneighboring scanning signal lines GL and two neighboring video signallines DL are two-dimensionally arranged, for example, a common bus lineCBL which is simultaneously formed with the video signal lines DL isformed. The common bus line CBL is formed on a surface of the TFTsubstrate SUB1 by way of a first insulation layer PAS1. Here, the firstinsulation layer PAS1 is an insulation layer which is interposed betweenthe scanning signal lines GL and the video signal lines DL in thedisplay region DA, and the first insulation layer PAS1 is interposedbetween the common bus line CBL and the scanning signal line GL in aregion where the common bus line CBL and the scanning signal lines GLintersect each other.

Further, on the common bus line CBL, a second insulation layer PAS2 andthe transparent conductive film TE are formed. Here, through holes TH1shown in FIG. 5, for example, are formed in the second insulation layerPAS2, and the transparent electrode TE is electrically connected withthe common bus line CBL which constitutes a conductive layer via thethrough holes TH1. Further, the transparent conductive film TE iselectrically connected to common signal lines CL, holding capacitancelines or the like which are arranged parallel to the scanning signallines GL via through holes TH2. Further, the transparent conductive filmTE is made of a transparent electrode material in the same manner as thepixel electrodes formed in the pixel regions, wherein the transparentelectrode TE is preferably made of ITO.

Further, in the liquid crystal display panel of this embodiment, in theTFT substrate SUB1, as shown in FIG. 5 and FIG. 6, apart from thethrough holes TH1, TH2, recessed grooves GV are formed in the secondinsulation layer PAS2 formed on the common bus line CBL. The recessedgrooves GV are covered with the transparent conductive film TE, and afirst orientation film outer periphery restricting portion Z1 isconstituted of these recessed grooves GV and the transparent conductivefilm TE. Here, the recessed grooves GV which constitute the firstorientation film outer periphery restricting portion Z1 are, as shown inFIG. 5, constituted of a combination of elongated grooves which extendin the direction (y direction) along the outer periphery of the displayregion DA, grooves which are bent in the x direction orthogonal to the ydirection and grooves which are bifurcated. Further, the recessedgrooves GV form a pattern of grooves formed between two neighboringscanning signal lines GL as a unit, and each pattern is formed for everyspace defined between two neighboring scanning signal lines GL.

FIG. 7 and FIG. 8 are schematic views similar to FIG. 5 and FIG. 6 forexplaining a function of the first orientation film outer peripheryrestricting portion in this embodiment. FIG. 7 is a view for explainingspreading of the orientation film material ink when such a material inkis applied. FIG. 8 is a schematic cross-sectional view taken along aline C-C′ in FIG. 7. Here, FIG. 7 is a plan view showing a portion ofthe first orientation film outer periphery restricting portion of theTFT substrate in the region AR1 shown in FIG. 1 in an enlarged manner.

In this embodiment, in forming the orientation film on the TFT substrateSUB1, for example, using an inkjet printing method or the like, a resinmaterial ORI (orientation film material ink) in a liquid form is appliedonly on the display region DA and on a slight region around the displayregion DA and is baked. Here, the orientation film material ink ORI in aliquid form which is applied using the inkjet printing method, asindicated by a bold arrow in FIG. 7, spreads by wetting in the directiontoward outside from the display region DA, that is, toward a sealingregion SL shown in FIG. 1. Further, in a case of a conventional TFTsubstrate SUB1, in a region close to a gate side a of the TFT substrateSUB1, the orientation film material ink ORI in a liquid form easilyspreads by wetting along the extending direction of the scanning signallines GL and reaches a sealing region.

However, in this embodiment, due to the provision of the firstorientation film outer periphery restricting portion Z1 formed on theTFT substrate SUB1, when the orientation film material ink ORI spreadsby wetting in the direction toward the gate side a from the displayregion DA, the orientation film material ink ORI passes the recessedgroove GV of the second insulation layer PAS2 and the transparentconductive film TE before reaching the sealing region SL. Here, theorientation film material ink ORI which reaches the recessed groove GVby spreading by wetting, as shown in an upper stage of FIG. 8, does notflow into the recessed groove GV initially and flows while obviating therecessed groove GV and hence, the flow of the orientation film materialink ORI can be controlled (along with a lapse of time, as shown in alower stage of FIG. 8, ink falls into the inside of the recessed grooveGV). Here, since the orientation film material ink ORI exhibits the poorwettability with the transparent conductive film TE, when thetransparent conductive film TE preferably made of ITO is mounted on thesurface of the recessed groove GV, spreading by wetting of theorientation film material ink ORI in a liquid form can be furthersuppressed by the recessed groove GV. Although one recessed groove GVmay obtain a spreading preventing effect to some extent, it is desirableto provide a plurality of recessed grooves GV.

However, depending on a coating quantity, viscosity, coating atmosphereof the orientation film material ink ORI corresponding to a size of theliquid crystal display panel, there may be a case that the orientationfilm material ink ORI reaches the region SL in which the sealingmaterial is arranged while getting over the first orientation film outerperiphery restricting portion Z1. In this embodiment, as explained inconjunction with FIG. 3 and FIG. 4, due to the second orientation filmouter periphery restricting portion Z2 which is formed in a portionclose to the inside of the sealing region SL at the position away fromthe first orientation film outer periphery restricting portion Z1 in thescanning line terminal GLT direction, it is possible to prevent theorientation film material ink ORI which spreads by wetting while gettingover the first orientation film outer periphery restricting portion Z1from reaching the sealing region SL.

FIG. 9 is explanatory views of the second orientation film outerperiphery restricting portion Z2, wherein the upper stage of FIG. 9 is aplan view of the second orientation film outer periphery restrictingportion Z2 and the lower stage of FIG. 9 is a cross-sectional viewshowing an essential part in FIG. 9A in an enlarged manner. The secondorientation film outer periphery restricting portion Z2 is formed of aplurality of slits ST which are formed by linearly removing thetransparent conductive film TE formed on the second insulation layerPAS2. Here, the transparent conductive film TE extends from the firstorientation film outer periphery restricting portion Z1, and terminateson a sealing region SL side of the second orientation film outerperiphery restricting portion Z2 and does not reach the sealing regionSL. Although one slit ST may obtain a spreading preventing effect tosome extent, it is desirable to provide a plurality of slits ST tosurely prevent spreading by wetting of the orientation film material inkORI.

Embodiment 2

FIG. 10 is a plan view of an essential part of a drain side of a TFTsubstrate indicated by symbol AR2 in FIG. 1 which schematically showsthe schematic constitution of a liquid crystal display panel of anembodiment 2 according to the present invention. Further, FIG. 11 is aschematic plan view showing the schematic constitution of a region AR3shown in FIG. 10 in an enlarged manner. FIG. 12 is a schematiccross-sectional view taken along a line D-D′ in FIG. 11. FIG. 13 is aschematic plan view showing the schematic constitution of a region AR4shown in FIG. 10 in an enlarged manner. FIG. 14 is a schematiccross-sectional view taken along a line E-E′ in FIG. 13.

In the liquid crystal display panel of this embodiment, to observe anouter peripheral portion of the display region DA of the TFT substrateSUB1 close to the drain side c in an enlarged manner, as shown in FIG.10, outside the display region DA, a common bus line CBL is formed alongthe outer periphery of the display region DA. Here, the common bus lineCBL is simultaneously formed with the scanning signal lines GL, and thefirst insulation layer PAS1 is interposed between the common bus lineCBL and the video signal lines DL.

Further, a region which is arranged outside the common bus line CBL asviewed from the display region DA and in which the video signal lines DLare collectively arranged, as shown in FIG. 10 to FIG. 12, includes aregion PDs where protective diodes are formed. Here, in the region PDswhere the protective diodes are formed, as shown in FIG. 11 and FIG. 12,a third orientation film outer periphery restricting portion Z3 which isconstituted of the recessed grooves GV which are formed in a firstinsulation layer PAS1 and a second insulation layer PAS2 and thetransparent conductive film TE which covers the recessed grooves GV isformed.

Further, on the drain side c of the liquid crystal display panel, forexample, as shown in FIG. 10, a common input pattern CIPB for applying acommon voltage to the common bus line CBL is formed. The common inputpattern CIP is simultaneously formed with the scanning signal lines GL.In a region where the common input pattern CIP is formed, for example,as shown in FIG. 13 and FIG. 14, a groove portion which is constitutedof a recessed groove GV which is formed in the second insulation layerPAS2 and the first insulation layer PAS1 and reaches the common inputpattern CIP and the transparent conductive film TE which covers therecessed groove GV is formed.

FIG. 15 is a schematic cross-sectional view for explaining a function ofa third orientation film outer periphery restricting portion Z3 forsuppressing a spreading by wetting of the orientation film material ink.Here, a common input pattern CIP also has a similar function ofsuppressing spreading by wetting of the orientation film material ink.FIG. 15 is a view as viewed on the same cross section as FIG. 12.

In forming the orientation film on the TFT substrate SUB1, for example,the orientation film material ink ORI in a liquid form is applied onlyto the display region DA and a slight region around a periphery thereofusing an inkjet printing method. The applied orientation film materialink ORI spreads by wetting substantially isotropically in the directiontoward the outside where the sealing region SL is arranged from thedisplay region DA and, at the same time, the orientation resin materialink ORI also spreads by wetting in the direction toward the drain side cfrom the display region DA.

However, due to the provision of the groove portion which is constitutedof the recessed groove GV which is formed in the third orientation filmouter periphery restricting portion Z3 and the common input pattern CIPand the transparent conductive film TE which covers the recessed grooveGV formed on the TFT substrate SUB1 of this embodiment, even when theorientation film material ink ORI spreads by wetting in the directiontoward the drain side c from the display region DA, the orientationresin material ink ORI cannot flow into the recessed groove GV beforereaching the sealing region SL and flows while avoiding the recessedgroove as shown in FIG. 15 and hence, the flow of the orientation resinmaterial ink ORI is suppressed. Further, since the orientation filmmaterial ink ORI in a liquid form exhibits poor wettability with thetransparent conductive film TE and hence, the spreads by wetting of theorientation film material ink ORI can be further suppressed orprevented.

FIG. 16 is a schematic plan view for explaining a modification of thegroove portion formed on the drain side of the TFT substrate. FIG. 17 isa schematic cross-sectional view taken along a line F-F′ in FIG. 16.

In the constitution shown in FIG. 13 and FIG. 14, the common inputpattern CIP is a so-called matted pattern and hence, a surface of thesecond insulation layer PAS2 around the groove portion is flat.Accordingly, only with the provision of such groove portion, thereexists a possibility that the spreading by wetting of the orientationresin material ink ORI in a liquid form cannot be stopped.

Accordingly, as shown in FIG. 16 and FIG. 17, it is preferable to formslits ST in the common input pattern CIP. By forming the slits ST inthis manner, as shown in FIG. 17, a stepped portion is generated betweena portion of the TFT substrate SUB1 where the common input pattern CIPis interposed and a portion of the TFT substrate SUB1 where the commoninput pattern CIP is not interposed thus suppressing the spreading bywetting of the orientation film material ink ORI.

FIG. 18 is a plan view of an essential part of the drain side of the TFTsubstrate indicated by symbol AR3 in FIG. 10 in the same manner as FIG.11 which explains the modification of the third orientation film outerperiphery restricting portion Z3 formed on the liquid crystal displaypanel of the embodiment 2 according to the present invention. FIG. 19 isa partially enlarged view of a part of the third orientation film outerperiphery restricting portion Z3 in FIG. 18.

In such a constitution, between the display region on which theplurality of video signal lines DL are formed and the region where thesealing agent is arranged, a protective diode forming region PDs whichconnects a plurality of respective video signal lines using a diodecircuit with each other is formed. Then, between the sealing region sideof the plurality of video signal lines DL and the protective diodeforming region PDs, the third orientation film outer peripheryrestricting portion Z3 where the plurality of recessed grooves GV andthe transparent conductive film TE extend on the inner surface and thebottom surface of the recessed groove GV is formed.

In such a constitution, the plurality of recessed grooves GV whichconstitutes the third orientation film outer periphery restrictingportion Z3 is arranged in a portion elongated in the direction parallelto an outer periphery of the display region DA and, is arranged in astaggered manner to engage with each other. Then, the video signal linesDL which traverse the third orientation film outer periphery restrictingportion Z3 are arranged in a zigzag manner through spaces definedbetween the plurality of recessed grooves GV which are arranged in thestaggered manner. The transparent conductive film TE is made of the sameconductive material such as ITO. The transparent conductive film TE isconnected to the common input pattern CIP by connecting the plurality ofrecessed grooves GV with each other. By providing the recessed groovesGV in multi stages as described above, it is possible to surely suppressspreading by wetting of the orientation film material ink ORI.

FIG. 20 is a plan view of an essential part of the drain side of the TFTsubstrate indicated by symbol AR3 in FIG. 10 in the same manner as FIG.18 which explains another modification of the third orientation filmouter periphery restricting portion Z3 formed on the liquid crystaldisplay panel of the embodiment 2 according to the present invention.FIG. 21 is a partially enlarged view of a part of the third orientationfilm outer periphery restricting portion Z3 in FIG. 20.

Also in the constitution of this modification, between the displayregion on which the plurality of video signal lines DL are formed andthe region where the sealing agent is arranged, a protective diodeforming region PDs which connects a plurality of respective video signallines using a diode circuit with each other is formed. Then, between thesealing region side of the plurality of video signal lines DL and theprotective diode forming region PDs, the third orientation film outerperiphery restricting portion Z3 where the plurality of recessed groovesGV and the transparent conductive film TE extend on the inner surfaceand the bottom surface of the recessed groove GV is formed.

In such a constitution, the plurality of recessed grooves GV whichconstitutes the third orientation film outer periphery restrictingportion Z3 is arranged in a portion elongated in the direction parallelto an outer periphery of the display region DA and, is arranged toengage with each other. At the same time, the recessed grooves GV areformed with a small length in the protective diode forming region PDsand a large length in the sealing region side. Then, the video signallines DL which traverse the third orientation film outer peripheryrestricting portion Z3 are arranged in a zigzag manner through spacesdefined between the plurality of recessed grooves GV. The transparentconductive film TE is made of the same conductive material such as ITO.The transparent conductive film TE is connected to the common inputpattern CIP by connecting the plurality of recessed grooves GV with eachother.

With the constitution of the third orientation film outer peripheryrestricting portion Z3 shown in FIG. 20 and FIG. 21, even when thenumber of stages of recessed grooves GV is small, the recessed groove GVwhich is formed with a large length on the sealing region side cansurely suppress the spreading by wetting of the orientation filmmaterial ink ORI.

FIG. 22 is a schematic plan view showing the schematic constitution ofthe TFT substrate in a region AR5 shown in FIG. 1 in an enlarged manner.FIG. 23 is a schematic cross-sectional view taken along a line G-G′ anda line H-H′ in FIG. 22 respectively.

The explanation heretofore is made with respect to the method forcontrolling the spreading by wetting of the orientation resin materialink ORI in the vicinity of the gate side a and the drain side c of theTFT substrate SUB1. The present invention is not limited to the controlof spreading by wetting of the orientation film material ink ORI in thevicinity of the gate side “a” and the drain side “c” of the TFTsubstrate SUB1 and is also applicable to the control of spreading bywetting of the orientation film material ink ORI in the vicinity of theother side of the TFT substrate SUB1. Hereinafter, a method forcontrolling spreading by wetting of the orientation resin material inkORI in the vicinity of an opposite gate side “b” and opposite drain side“d” of the TFT substrate SUB1 is explained.

At a corner portion where the opposite gate side “b” and the oppositedrain side c abut each other in the TFT substrate SUB1, for example, asshown in FIG. 22, a common bus line CBL is arranged outside the displayregion DA along the outer periphery of the display region DA. The commonbus line CBL is formed simultaneously with the scanning signal lines GLand, as shown in FIG. 23, is arranged between the TFT substrate SUB1 andthe first insulation layer PAS1.

Further, on a portion of the common bus line CBL along the opposite gateside b, an elongated groove portion which extends in the direction alongthe opposite gate side b is formed. On a portion of the common bus lineCBL along the opposite drain sided, an elongated groove portion whichextends in the direction along the opposite drain side d is formed.These two groove portions are continuously formed at the corner portionof the common bus line CBL.

Further, the groove portions formed along the opposite gate side b andthe opposite drain side d are, for example, as shown in FIG. 23,respectively constituted of a recessed groove GV which is formed in thefirst insulation layer PAS1 and the second insulation layer PAS2 whichare stacked on the common bus line CBL and the transparent conductivefilm TE which covers the recessed groove GV. Here, it is preferable toset a length of the recessed groove GV in the direction along theopposite gate side b to a value larger than a distance between twoscanning signal lines which are arranged at outermost sides out of theplurality of scanning signal lines. In the same manner, it is preferableto set a length of the recessed groove GV in the direction along theopposite drain side d to a value larger than a distance between twovideo signal lines which are arranged at outermost sides out of theplurality of video signal lines. Here, the transparent electrode TE is,for example, as shown in FIG. 22, formed such that the transparentconductive film TE covers the whole common bus line CBL in a plan view.

Due to such a constitution, also when the applied orientation resinmaterial ink ORI in a liquid form spreads by wetting in the directiontoward the opposite gate side b and the opposite drain side d from thedisplay region DA, before reaching the sealing region SL, theorientation film material ink ORI in a liquid form passes the grooveportion constituted of the recessed groove GV formed in the secondinsulation layer PAS2 and the first insulation layer PAS1 and thetransparent conductive film TE. Accordingly, the orientation filmmaterial ink ORI which spreads by wetting and reaches the groove portioncannot flow into the recessed groove GV thus flowing along the recessedgroove GV. Further, the orientation film material ink ORI in a liquidform exhibits low wettability to the transparent conductive film TE andhence, by forming the transparent conductive film TE made of ITO on thesurface of the groove portion, the spreading by wetting of theorientation film material ink ORI can be suppressed by the grooveportion.

Further, in the constitutional example shown in FIG. 22, one grooveportion is formed. However, it is needless to say that the constitutionof the groove portion is not limited to such a case and double grooveportions or triple groove portions may be formed toward the sealingregion SL from the display region DA.

FIG. 24 is a schematic cross-sectional view for explaining anothermodification of the groove portions formed in the opposite gate side andthe opposite drain side of the TFT substrate. FIG. 25 is a schematiccross-sectional view for explaining still another modification of thegroove portions formed in the opposite gate side and the opposite drainside of the TFT substrate. FIG. 26 is a schematic cross-sectional viewfor explaining still another modification of the groove portions formedin the opposite gate side and the opposite drain side of the TFTsubstrate.

In FIG. 22 and FIG. 23, a case in which the transparent conductive filmTE is formed such that the transparent electrode TE covers whole commonbus line CBL in a plan view is exemplified. However, it is needless tosay that the constitution of the transparent electrode is not limited tosuch a case and, for example, as shown in FIG. 24, the transparentconductive film TE may be formed only on and around the recessed grooveGV which is formed in the first insulation layer PAS1 and the secondinsulation layer PAS2.

Further, in FIG. 22 and FIG. 23, a case in which the common bus line CBLis formed simultaneously with the formation of the scanning signal linesGL is exemplified. However, it is needless to say that the common busline CBL may be formed simultaneously with the formation of the videosignal lines DL. In such a case, the groove portion is, for example, asshown in FIG. 25, constituted of a recessed groove GV which is formed inthe second insulation layer PAS2 and the transparent conductive film TEwhich is formed on the surface of the second insulation layer PAS2.Further, for example, as shown in FIG. 26, the transparent conductivefilm TE may be formed only on and around the recessed groove GV.

As has been explained heretofore, according to the embodiment, in theTFT substrate SUB1, in the substantially annular region which isarranged inside the sealing region SL and outside the display region DA,the groove portion which is constituted of the recessed grooves GVformed in the insulation layer and the transparent conductive film TEwhich extends along the side surfaces and the bottom surfaces of theinside of the recessed grooves GV is formed. Accordingly, in forming theorientation film of the liquid crystal display panel, it is possible tosuppress the spreading by wetting of the orientation film material inkORI outside the display region and, at the same time, by suppressingunnecessary spreading by wetting, it is possible to maintain theuniformity of the film thickness of the orientation film in the insideof the display region.

FIG. 27 to FIG. 29 are schematic views showing one constitutionalexample of one pixel which is formed in the display region of the liquidcrystal display panel of this embodiment. FIG. 27 is a schematic planview showing one constitutional example of one pixel of the displayregion of the TFT substrate as viewed from a viewer's side. FIG. 28 is aschematic cross-sectional view taken along a line J-J′ in FIG. 27. FIG.29 is a schematic cross-sectional view taken along a line K-K′ in FIG.27.

When the liquid crystal display panel of this embodiment adopts alateral electric field driving method which is referred to as an IPSmethod, the pixel electrodes PX and the counter electrodes CT are formedon the TFT substrate SUB1. Further, the IPS method is classified into,for example, a method in which the pixel electrodes PX and the counterelectrodes CT having a comb-teeth shape in a plan view are arranged onthe same layer, that is, on the same insulation layer and a method inwhich the pixel electrodes PX and the counter electrodes CT are arrangedon a surface of the substrate in parallel to each other by way of aninsulation layer. Out of these methods, in case of the IPS method whicharranges the pixel electrodes and the counter electrodes in parallel toeach other by way of the insulation layer, one pixel of the TFTsubstrate is, for example, constituted in the same manner as theconstitution shown in FIG. 27 to FIG. 29.

In FIG. 27 to FIG. 29, on the surface of the TFT substrate SUB1preferably made of glass, a plurality of scanning signal lines GL whichextends in the x direction, common signal lines CL which are arranged inparallel to the respective scanning signal lines GL and counterelectrodes CT which are connected to the common signal lines CL areformed. Here, the respective common signal lines CL are, for example, asshown in FIG. 5, connected to the common bus line CBL outside thedisplay region DA. Further, on a side opposite to the direction alongwhich the common signal lines CL are arranged as viewed from thescanning signal lines GL, common connection pads CP which are connectedto the counter electrodes CT are formed.

Then, on the scanning signal lines GL, the counter electrodes CT and thelike, the semiconductor layers SC, the video signal lines DL, the drainelectrodes SD1, and the source electrodes SD2 are formed by way of thefirst insulation layer PAS1. Here, the semiconductor layers SC are madeof amorphous silicon (a-Si), for example. The semiconductor layers SCinclude, besides semiconductor layers SC which function as channellayers of the TFT elements, for example, semiconductor layers SC whichprevent short-circuiting between the scanning signal lines GL and thevideo signal lines DL at portions where the scanning signal lines GL andthe video signal lines DL three-dimensionally intersect with each other.Further, in this case, the semiconductor layers SC which function aschannel layers of the TFT are formed on the scanning signal lines GL byway of the first insulation layer PAS1, and the first insulation layerPAS1 which is interposed between the scanning signal lines GL and thesemiconductor layers SC functions as a gate insulation film of the TFT.

Further, the video signal lines DL are signal lines which extend in they direction and portions of the video signal lines DL are bifurcated andare formed on the semiconductor layer SC which functions as channellayers of the TFT. The portions which are bifurcated from the videosignal lines DL constitute the drain electrodes SD1.

On the semiconductor layers SC, the video signal lines DL and the like,the pixel electrodes PX and bridge lines BR are formed by way of asecond insulation layer PAS2. The pixel electrodes PX are electricallyconnected with the source electrodes SD2 via through holes TH3. Further,the pixel electrode PX forms a plurality of slits (opening portions) PSLin a region thereof which overlaps the counter electrode CT in a planview.

Further, the bridge line BR is a line which electrically connects twocounter electrodes CT which are arranged with one scanning signal lineGL therebetween. The bridge line BR is electrically connected with acommon signal line CL and a common connection pad CP which are arrangedwith the scanning signal line GL sandwiched therebetween via throughholes TH4, TH5.

Here, it is needless to say that the TFT substrate SUB1 in the liquidcrystal display panel according to the present invention is not limitedto the case in which one pixel has the particular constitution and isapplicable to the TFT substrates having various constitutions known ingeneral conventionally.

Although the present invention has been explained specifically inconjunction with the best mode for carrying out the invention, thepresent invention is not limited to any one of the above-mentionedembodiments and various modifications are conceivable without departingfrom the technical concept of the present invention.

For example, in this embodiment, the explanation is made with respect toan example which provides the groove portion which suppresses thespreading by wetting of the orientation film material ink on the TFTsubstrate SUB1 of the liquid crystal display panel. However, the presentinvention is not limited to the TFT substrate and is also applicable toa formation of the orientation film of the counter substrate.

When the liquid crystal display panel adopts the vertical electric fielddrive method such as the TN method or the VA method, a counter electrodeCT is formed on the counter substrate. In this case, a black matrix(light blocking pattern) and color filters are formed on a surface of aglass substrate, and the counter electrode is formed on these blackmatrix and the color filters by way of an overcoat layer, for example.Accordingly, by forming the groove portion in such a manner thatrecessed grooves which are formed in the overcoat layer are formed in aregion inside a region where the sealing material is arranged andoutside the display region in forming the overcoat layer and the counterelectrode extends on surfaces of the recessed grooves, it is possible toprevent the spreading by wetting of the orientation film by the grooveportion.

1. A liquid crystal display device having a display panel in which anannular sealing material is arranged between a pair of substrates, aliquid crystal material is sealed in a space surrounded by the pair ofsubstrates and the sealing material, a display region is formed in theinside of a region surrounded by the sealing material in a plan view,and signal lines which extend to the outside of the sealing materialfrom the inside of the display region is formed on one of thesubstrates, wherein the pair of substrates have orientation films onsurfaces thereof which face opposing substrates, out of the pair ofsubstrates, the substrate on which the signal lines are formed, on aside thereof which is disposed between a region on which the sealingmaterial is arranged and the display region and along which the signallines extend to the outside of the sealing material from the displayregion, includes a first conductive layer, a second conductive layer andan insulation layer which is interposed between the first and secondconductive layers between the orientation film and the substrate, theinsulation layer extends in the direction at least along an outerperiphery of the display region, and includes a groove portion having arecessed groove which opens on the orientation film side, the firstconductive layer is formed along a shape of the recessed groove, and thesignal lines are formed in a state that the signal lines go around therecessed groove.
 2. A liquid crystal display device according to claim1, wherein the signal lines are either one of scanning signal lines orvideo signal lines.
 3. A liquid crystal display device according toclaim 1, wherein the substrate which includes the groove portionincludes a plurality of scanning signal lines, a plurality of videosignal lines which three-dimensionally intersects the plurality ofscanning signal lines, and a TFT element and a pixel electrode which arearranged in each pixel region surrounded by two neighboring scanningsignal lines and two neighboring video signal lines, and the firstconductive layer is made of the same material as the pixel electrodes.4. A liquid crystal display device according to claim 3, wherein thefirst conductive layer and the pixel electrode are made of ITO.
 5. Aliquid crystal display device according to claim 1, wherein the secondconductive layer forms a portion of a protective diode, and a region inwhich the protective diode is formed is formed along the display regionbetween a region on which the sealing material is arranged and thedisplay region.
 6. A liquid crystal display device according to claim 5,wherein the protective diode is formed between the signal line whichextends in the inside of the display region and the signal line whichextends to the outside of the sealing material.
 7. A liquid crystaldisplay device according to claim 6, wherein the recessed groove isformed between the protective diode and the sealing material.
 8. Aliquid crystal display device according to claim 6, wherein the recessedgroove is formed in at least two or more rows per one signal line.
 9. Aliquid crystal display device according to claim 7, wherein theplurality of recessed grooves formed in the substrate has the same size.10. A liquid crystal display device according to claim 7, wherein theplurality of recessed grooves formed in the substrate is formed suchthat the closer to the sealing material, a size of the recessed grooveis increased.
 11. A liquid crystal display device according to claim 1,wherein the recessed grooves have portions which are elongated in thedirection parallel to the outer periphery of the display region, and arearranged in a staggered pattern to be engaged with each other.
 12. Aliquid crystal display device according to claim 11, wherein the signallines are arranged in a zigzag manner passing between the plurality ofrecessed grooves arranged in a staggered pattern.